The present invention relates to a low-pressure die-casting apparatus.
Conventional low-pressure die-casting apparatuses are usually constituted by a flowing furnace into which a tube is immersed in order to dispense, by feeding pressure into the furnace, the liquid metal into a die which is connected in an upward region to the metal draw tube.
In order to form hollow bodies, such as for example faucets and the like, a molding-sand core is arranged inside the die; the core must be destroyed, for example by simple shaking, once casting is completed.
At the furnace there is usually a handling unit which allows to perform the various handlings of the die and to load the cores, unload the cast part and perform all the operations for the graphitization and cooling of the dies.
The die is loaded so that the molten metal must enter it from below, because if the molten metal were to enter from above it would prevent the escape of the air and bubbles would therefore form which would reduce the quality of the finished product.
As mentioned above, the furnace has a tube which enters its crucible to draw in the vicinity of the bottom and in any case with a head which is sufficient to perform a certain number of die filling operations before having to open the furnace and introduce further material to be melted.
In conventional methods, the die is carried by a handling unit exactly above the furnace, as occurs for example in the Italian patent application no. MI96A001138 in the name of the same applicant, is made to descend vertically above it until its lower part, in which there is a hole through which the molten material must enter, makes contact with the tube that draws from the furnace.
Casting occurs by pressurizing the furnace by means of compressed air or another inert gas, so that the liquid metal rises along the tube, filling the entire die.
This method, however, required a very complicated handling unit.
Said handling unit, when it moves from the position above the furnace toward the discharge region, must in fact open in order to allow the exit of the finished product but must also rotate the die halves that constitute the die in order to place them in front of the operator.
In addition to this, the handling unit must be able to overturn the two die halves to allow graphitization and washing and cleaning of all the slag.
Accordingly, the handling unit must have the ability to perform a translatory motion and also to move downwards.
In the system described by the above-mentioned patent application no. MI96A001138 there are two furnaces and the handling unit must operate by moving to one region and then to the other and is accordingly very complicated.